Variation in Mental Foramen of Mandible among South Indian Population- A Radiographic Analysis

Background: The mental foramen (MF) is a hole in the body of the mandible that is placed on the antero-lateral side. Between the upper and lower mandibular borders, it can be found. It sends signals to the brain's nerves and blood vessels. Many researches have documented variations in the placement of the MF among different ethnic groups, as well as variations in its forms. It's commonly found beneath the first premolar teeth. The study's goal is to look at where mental foramen are found in the South Indian population. Materials and Methods: A total of 100 distinct OPGs from the South Indian population were used in the investigation. The position of mental foramen for various mandibles was visually examined using OPGs, and the data was tallied and analyzed using SPSS. Results: From the results it is suggested that the maximum frequency for the right side is at location 2 which is in the longitudinal axis of 1st premolar. 14.0% at location 1, 31.6% at location 2, 21.1% at location 3. 17.3% at location 4. 10% at location 5, 6% at location 6. The situation of mental foramen at the axis of 1st premolar was observed to have a high frequency of occurrence in the age group of 26-35. Conclusion: The Mental foramen in study population is mostly found in the longitudinal axis of 1st premolar. The clinical students and surgeons should know the existence of mental foramen at surgical procedures using mandibular premolar and molar regions. Future studies with large sample sizes should be conducted to make the results conclusive. Original Research Article Ashwin and Prathap; JPRI, 33(60B): 3473-3479, 2021; Article no.JPRI.78958 3474


INTRODUCTION
The Mental Foramen (MF) is placed midway between the top and bottom margins of the mandible's body. It runs parallel to the supraorbital notch between the two premolars. The foramen is the departure point for mental vessels and nerves [1]. An orthopantomogram can be used to determine the position of the mental foramen (OPG). The mental foramina are usually depicted in a postero-superior position. Many studies have shown that the MF is placed differently in different ethnic groups, as well as in distinct shapes. It's usually seen under the first premolar. The branches of the mental nerve and veins may use this mental foramen. Dental surgeons would benefit greatly from fine knowledge of the variations in the different dimensions of the mental foramen, and thus the appearance of the accessory mental foramen, when performing surgical procedures on the mandible, [2] Prior to surgery, it is also critical to have an effective and successful anaesthesia during nerve blocks. Various authors have reported on numerous studies on the South Indian people. As a result, we attempted to discover the most common position and size of the mental foramen in adult South Indians in our current study [3]. The experience from our previous studies [4][5][6][7][8][9][10][11][12][13] have led us to focus on the current topic.
MF is usually single in human beings; If Accessory mental foramen is present, MF transmit either the accessory mental nerve, which It iself may be a branch of inferior alveolar nerve, or one among the branches of mental nerve [14]. These auxiliary mental foramen (AMFs) are located on the perimandibular area surrounding the MF and are usually smaller than the MF. Failure to detect and protect MF and the structures that cross it would be the reason for a lack of proper mental nerve anaesthesia. It can cause neurosensory problems or traumatic neuroma if the accessory nerves are accidentally damaged. Our team has a wealth of research and knowledge that has resulted in high-quality publications [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. The study's goal is to look at where mental foramen are found in the South Indian population.

MATERIALS AND METHODS
This is a retrospective study conducted in a private dental college and hospital in chennai using 100 OPG's. Patients aged 1 year and above and High quality OPG's with respect to coloration and angulation were included. Exclusion criteria-Patients affected with dental and maxillofacial fractures, joint disjunction, traumas, pathological lesions around mental foramen were excluded and Patients undergoing diagnosis surgery or orthodontic purposes were excluded from the study. Data were analyzed statistically by SPSS 2.3. Data was set and analysed by chi square test with bar charts and cross tabs. The study was approved by the institutional review board. The OPG'S of the South Indian population were taken and the location of the mental foramen is located and the data were added in sheets and statistically analysed in SPSS. The locations were classified by 6 different locations ( Table 1). The locations were entered and statistically analysed by SPSS. Axis of 1st premolar 3 Between 1st and 2nd premolar 4 Axis of 2nd premolar, 5 Between 2nd premolar and 1st molar 6 Axis of 1st molar.

RESULTS
From the results it is suggested that the maximum frequency for the right side is at location 2 which is in the longitudinal axis of 1st premolar. 14.0% at location 1, 31.6% at location 2, 21.1% at location 3. 17.3% at location 4. 10% at location 5, 6% at location 6. The location of mental foramen at the axis of 1st premolar was observed to have a high frequency of occurrence in the age group of 26-35. (Figs. 1,2 represented in different age groups with error bars).

DISCUSSION
The location of the vertical axis of the 1st premolar has the maximum frequency among the 100 OPG's in the South Indian population. The Most frequent frequency was 14.0% at location 1, 31.6% at location 2, 21.1% at location 3. This study can have It is own relevance and has forensic importance [35,36]. The MF is typically directed postero-superiorly and is situated on the anterolateral aspect of the body of the mandible. It is usually located below the interval between the premolars, midpoint between the inferior and the alveolar margins of the mandible, and approximately thirteen to fifteen millimeter superior to the inferior border of the mandibular body. Variations are observed in It is location, which may be more anterior, below the canine or posterior, and close to the second molar [37]. MFs are typically seen underneath the primary molar and premolar teeth, according to previous research. Though it was found in a variety of places in the current investigation, it was found below the second premolar in 48 percent of the cases [38]. As previously stated, the bulk of the MF were found in the distal part of the MF, with only a few in the mesial region. The majority of the time, MF was discovered to be located inferior to the MF. AMF were found to be behind MF [39]. The presence of AMF in relation to MF could have an impact on the rehabilitation therapy planning since it would interfere with implant processes. The majority of the MF in this study were either inferolateral (25.9%) or superomedial (25.9%) to the MF [40].
The most common MF location in the anteriorposterior position, There was an edge inbetween the primary and 2nd mandibular premolars, which was typical of older patients on the right side, and then a situ within the vertical axis of the 2 nd mandibular premolars, which was typical on right side of younger patients, regardless of gender of the themes [41]. In every case when CT technologies were used, the outcomes of our studies matched the findings of the research. There were no changes in the dimensions of MF based on the age of the themes. However, significant differences in the dimension of MF were found in connection to the patients' gender. In comparison to women, men have a larger vertical dimension on two sides of the mandible and a larger horizontal dimension on the correct side of the jaw [42].
Dental implants and other surgery can be easily done by the identification of the mental foramen and it is location, preparation for the surgery can be easily made according to the requirements.
MF are a rare anatomical variation and reported to possess a prevalence starting from 1.4% to 10%. [43]. The presence of MF has been reported by investigations on dry human skulls, cadaveric dissections, and radiological studies. In a previous study, the incidence in the South Indian population was found to be 8.85%. % MF were found on the left side of the brain more than the right side in this study. This is consistent with prior research, which discovered 8% MFs on the left side and 5% on the right; 3.33 percent MFs on the left side and a few.22 percent on the right side. 4 MF were found on the right side of the mandible, according to [44] Bilateral MF has been documented in just 0.53 percent of the population, according to previous investigations [45]. In contrast, 2 percent of the South Indian population has been observed to have bilateral MF.
A study revealed 1.6% bilateral MF, indicating that bilateral MF occurrence is more in Indian population. The nerve flowing through the MF is hypothesised to influence the location and size of the MF. The mental nerve has four terminal branches: angular, medial inferior labial, lateral inferior labial, and mental branches [46]. The nerve emerging from MF has been described as either being one among the terminal branches of mental nerve given off within the mandibular canal or the presence of a further branch, called accessory mental nerve which is taken into account to be a branch of the inferior alveolar nerve which could have separated earlier than formation of mental foramina. Limitations of this study are limited sample size, random sampling, ethical issues in identifying opg's and names that can't be revealed and the data collected are highly confidential. Future studies should be conducted with a huge sample size to make the context evident and it may have forensic and surgical implications.

CONCLUSION
The Mental foramen in South Indian population is mostly found in the longitudinal axis of 1st premolar. The clinical students and surgeons should know the existence of mental foramen at surgical procedures using mandibular premolar and molar regions. To make the findings conclusive, other studies with large sample sizes should be done.

CONSENT
It's not applicable.

ETHICAL APPROVAL
As per international standard or university standard written ethical approval has been collected and preserved by the author(s).

ACKNOWLEDGEMENT
We thank Saveetha Dental College and Hospitals for the successful completion of the study.

COMPETING INTERESTS
Authors have declared that no competing interests exist.